FIG. 1 illustrates a prior art DC to AC converter 10 of the type utilized in airframes for converting a DC source to three phase alternating current. The converter 10 utilizes a conventional power inverter 12 which contains at least two pairs of power switches such as transistors (not illustrated) associated with each phase that are alternately switched on and off to produce a square wave having a fundamental frequency equal to the desired frequency of alternating current to be outputted on a phase output 14. An LC filter 16 is connected in series between the respective phase A, phase B, and phase C outputs of the power inverter and the phase outputs 14. The LC filter is comprised of an inductor 18 and a feed-through capacitor 20. The LC filter 16 attenuates frequency components present in the phase A, phase B and phase C outputs from the power inverter 12 to produce distinct phases of filtered alternating current at the fundamental frequency displaced 120.degree. apart from each other on the outputs 14. The power switches within the power inverter 12 are switched alternately on to connect the positive DC potential 22 and the negative DC potential 24 to the phase A, phase B and phase C outputs of the power inverter 12 with a phase displacement of 120.degree. from each other. The phase displaced squarewave outputs on the phase A, phase B and phase C outputs of the power inverter 12 contain substantial frequency components above the fundamental frequency of the squarewave. Each LC filter 16 functions such that the impedance of the inductor 18 attenuates frequency components higher than the fundamental frequency and the feedthrough capacitor 20 represents a low impedance to frequency components higher than the fundamental frequency which are shunted to the chassis 26 to cause the filtered outputs to be present on the phase outputs 14 without substantial frequency components above the fundamental frequency.
In applications of the power supply 10 in airframes 28, the capacity of the power supply is typically rated in kilowatts such as 75/90 kw per airframe propulsion engine. In variable speed constant frequency (VSCF) airframe power generator systems an alternator is driven by a power takeoff from an airframe propulsion engine to produce three phase variable frequency AC current which is rectified by a rectifier bridge to produce the DC potentials 22 and 24. In the aforementioned airframe applications the inductors 18 and capacitors 20 must be rated to handle substantial energy. As a result it is desirable for the inductors 18 to have a cooling apparatus to lower their operating temperature. Furthermore, the feedthrough capacitors 20 which are rated for the aforementioned high power applications may typically weigh two pounds or more which represents a weight and size penalty for airframe applications where saving of space and weight is of great importance in the overall efficient operation of the airframe. Accordingly, the prior art power supply 10 in high power generating applications in airframes suffers from the dual disadvantages that the inductors 18 require cooling to stabilize their operating temperature to provide longlife service conditions and further that the size of the individual feedthrough capacitors 20 represents a weight penalty.